UNIT -4 PRINCIPAL STRESSES AND STRAINS
1.A principal plane is a plane of (a) Zero tensile stress (b) Zero compressive stress (c) Zero shear stress (d) None (ANSWER: c) 2.A principal plane is a plane of (a) Only normal stress (b) Only shear stress (c) Only bending stress (d) None (ANSWER: a) 3.There are in all (a) Two principal planes (b) Three principal planes (c) Four principal planes (d) None (ANSWER: b) 4.There are in all (a) Two principal stresses (b) Three principal stresses (c) Four principal stresses (d) None (ANSWER: b) 5.There are in all (a) Two principal strains (b) Three principal strains (c) Four principal strains (d) None (ANSWER: b) 6.Identify the principal stress (a) Shear stress (b) Bending stress (c) Compressive stress (d) None (ANSWER:c) 7.On the planes of maximum shear, there are (a) Normal stresses (b) Bending stresses (c) Bucking stresses (d) None (ANSWER: a) 8.Maximum shear stress is (a) Average sum of principal stresses (b) Average difference of principal stresses (c) Average sum as well as difference of principal stresses (d) None (ANSWER: b) 9.The magnitude of principal stresses due to complex stresses is (a) (1/2)[ (σx + σy) ± ((σx –σy)2 + 4 τ2 ))0.5] (b) (1/2)[ (σx + σy) ± (1/2)((σx –σy)2 + 4 τ2 ))0.5] (c) (1/2)[ (σx + σy) ± ((1/2)(σx –σy)2 + 4 τ2 ))0.5] (d) None (ANSWER: a) 10.The equations in the various questions are valid only when (a)σx and σy are both tensile (b) σx is compressive and σy is tensile (c) σx is tensile and σy is compressive (d) None (ANSWER: a) 11.The magnitude of maximum shear stress will be (a) ± (1/2)[ ((σx –σy)2 + 4 τ2 ))0.5] (b) ± (1/2)[ (1/2)((σx –σy)2 + 4 τ2 ))0.5] (c) ± (1/2)[ ((1/2)(σx –σy)2 + 4 τ2 ))0.5] (d) None (ANSWER: a) 12.A complementary shear stress is equal in magnitude and opposite in rotational tendency of an applied (a) Tensile stress (b) Compressive stress (c) Shear stress (d) None (ANSWER:c) 13.All the principal stresses are at an angle of (a) 450 (b) 600 (c) 750 (d) None (ANSWER:d) 14.All the principal stresses are at an angle of (a)900 (b) 450 (g) 1350 (h) None ANSWER(a) 15.All the principal strains are at an angle of (a) 450 (b) 600 (c) 750 (d) None (ANSWER:d) 16.All the principal strains are at an angle oft (a) 450 (b) 900 (c) 1350 (d) None (ANSWER:b) 17.Total number of maximum shear stresses is (a) One (b) Three (c) Five (d) None (ANSWER: b) 18.All the maximum shear stresses are at an angle of (a)450 (b) 900 (c) 1350 (d) None (ANSWER:b) 19.Does a plane of maximum shear stress contain a (a) Normal stress (b) Bending stress (c) Torsional shear stress (d) None (ANSWER: a) 20.Mohr’ s circle is a graphical method to find (a) Bending stresses (b) Bucking stresses (c) Maximum shear stresses (d) None (ANSWER: c) 21.Mohr’ s circle is a graphical method to find (a) Bending stresses (b) Bucking stresses (c) Torsional shear stresses (d) None (ANSWER: d) 22.Mohr’ s circle is a graphical method to find (a) Bending stresses (b) Principal stresses (c) Torsional shear stresses (d) None (ANSWER: b) 23.Mohr’s stress circle method is used to analyze a body under (a) Complex stresses (b) Tensile and compressive stresses (c) Axial and longitudinal stresses (d) None (ANSWER:a) 24.When does Mohr’s stress circle method fail (a) the given two normal stresses are of the same magnitude and same nature (b)the given two normal stresses are of the same magnitude and are of opposite nature (c) the given two normal stresses are of the unequal magnitude and same nature (d) None (ANSWER: a) 25.The abscissa of the Mohr’s circle is a (a) Shear stress (b) Normal stress (c) Normal as well as shear stress (d) None (ANSWER: b) 26.The ordinate of the Mohr’s circle is a (a) Shear stress (b) Normal stress (c) Normal as well as shear stress (d) None (ANSWER: a) 27.The principal strain due to σ1(tensile) and σ2(Compressive ) stress will be (a) (1/E)( σ1 + σ2) (b) (1/E)( σ1 +µ σ2) (c) (1/E)( σ1 -µ σ2) (d) None (ANSWER: b) 28.The principal strain due to σ1 (compressive) and σ2 (tensile) stress will be (a) (1/E)( -σ1 + σ2) (b) (1/E)( -σ1 +µ σ2) (c) (1/E)(- σ1 -µ σ2) (d) None (ANSWER: c) 29.The relation between the elastic constant is (a) E = 2G (1–2µ) (b) E = 2G (1+2µ) (c) E = 2G (1+µ) (d) None (ANSWER:c) 30.The relation between the elastic constant is (a) E = 3 KG /(3K + G) (b) E = 6 KG / (3K + G) (c) E = 9GK /(3K + G) (d) None (ANSWER:c) 31.The relation between the elastic constant is (a) E = 3 K(1 – 2µ) (b) E = 6 K (1 – 2µ) (c) E = 9K(1 – 3µ) (d) None (ANSWER:a) 32.Resilience under principal tensile stresses σ1 and σ2 is (a) (1/2E)( σ12 + σ22 –3µ σ1 σ2) (b) (1/2E)( σ12 + σ22 –4µ σ1 σ2) (c) (1/2E)( σ12 + σ22 –5µ σ1 σ2) (d) None (ANSWER:d) 33.Resilience under principal tensile stresses σ1 and σ2 is (a) (1/2E)( σ12 + σ22 –3µ σ1 σ2) (b) (1/2E)( σ12 + σ22 –4µ σ1 σ2) (c) (1/2E)( σ12 + σ22 –5µ σ1 σ2) (d) None (ANSWER:d) 34.Resilience under principal tensile stresses σ1 and σ2 is (a) (1/2E)( σ12 + σ22 –µ σ1 σ2) (b) (1/2E)( σ12 + σ22 –4µ σ1 σ2) (c) (1/2E)( σ12 + σ22 –2µ σ1 σ2) (d) None (ANSWER:c) 35.Shear strain energy under principal tensile stresses σ1 and σ2 is (a) (1/12E) (σ1 — σ2)2 + σ22— σ12 ) (b) (1/12G) (σ1 — σ2)2 + σ22+ σ12 ) (c) (1/12K) (σ1 — σ2)2 + σ22+ σ12 ) (d) None (ANSWER:b) 36. The angle between normal stress and tangential stress is known as angle of ______ a. declination b. orientation c. obliquity d. rotation ANSWER: obliquity Explanation: No explanation is available for this question! 37. Principal stress is the magnitude of ________ stress acting on the principal plane. a. Normal stress b. Shear stress c. Both a. and b. d. None of the above ANSWER: Normal stress 38. When a component is subjected to axial stress the normal stress σn is maximum, if cos θ is _______ . (σn=σxCos2θ) 1. maximum 2. minimum 3. always one 4. always zero a. 1 and 4 b. 1 and 3 c. 2 and 3 d. 2 and 4 ANSWER: 1 and 3 39. Which of the following stresses can be determined using Mohr's circle method? a. Torsional stress b. Bending stress c. Principal stress d. All of the above ANSWER: Principal stress 40. The graphical method of Mohr's circle represents shear stress (τ) on ______ a. X-axis b. Y-axis c. Z-axis d. None of the above ANSWER: Y-axis 41. In Mohr's circle method, compressive direct stress is represented on ____ a. positive x-axis b. positive y-axis c. negative x-axis d. negative y-axis ANSWER: negative x-axis 42. What is the value of shear stress acting on a plane of circular bar which is subjected to axial tensile load of 100 kN? (Diameter of bar = 40 mm , θ = 42.3o ) a. 58.73 Mpa b. 40.23 Mpa c. 39.60 Mpa d. Insufficient data ANSWER: 39.60 Mpa 43. The maximum tangential stress σt = (σx sin 2θ)/2 is maximum if, θ is equal to ________ a. 45o b. 90o c. 270o d. all of the above ANSWER: 45o 44. Minor principal stress has minimum ________ a. value of shear stress acting on the plane b. intensity of direct stress c. both a. and b. d. none of the above ANSWER: intensity of direct stress 45. Which of the following formulae is used to calculate tangential stress, when a member is subjected to stress in mutually perpendicular axis and accompanied by a shear stress? a. [(σx – σy)/2 ]sin θ – τ cos 2θ b. [(σx – σy)/2 ]– τ cos 2θ c. [(σx – σy)/2 ]sin θ – τ 2 cos θ d. None of the above ANSWER: [(σx – σy)/2 ]sin θ – τ cos 2θ 46-Principal planes are those planes on which a. Normal stress is maximum b. Normal stress is minimum c. Normal stress is either maximum or minimum d. Shear stress is maximum (ANSWER: c) 47-In a general two dimensional stress system, there are a. Two principal planes b. Only one plane c. Three principal planes d. No principal plane (ANSWER: a) 48-Principal planes are mutually inclined at a. 45 degree b. 60 degree c. 90 degree d. 180 degree (ANSWER: c) 49-In a general two dimensional stress system, planes of maximum shear stress are inclined at ___ with principal planes. a. 90 degree b. 180 degree c. 45 degree d. 60 degree (ANSWER: c) 50-In a general two dimensional stress system, the planes on which shear stress is zero a. The normal stress is minimum b. Normal stress is zero c. Normal stress is either maximum or minimum d. None of these (ANSWER: c) 51-Ellipse of stress is used to find a. Resultant stress on any plane in a bi-axial stress system b. Resultant stress on any plane in a general two dimensional system c. Maximum shear stress d. Location of planes of maximum shear stress (ANSWER: a) 52-In Mohr’s circle of strain, y-axis represents a. Shear strain b. Half of shear strain c. Normal strain d. Half of normal strain (ANSWER: b) 53-In a general two dimensional stress system, Ellipse of stress can find a. Principal planes b. Principal stresses c. Planes of maximum shear stress d. Resultant stress on any plane (ANSWER: d
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